The concept of separating entrained solids from gases by passing such gases through a mass of solid particulate material is not a new one. It is described in "Chemical Engineer's Handbook" (Perry, 4th Edition, McGraw-Hill) at pages 20-74. Specific applications of the concept are described in numerous patents. Each of U.S. Pat. Nos. 890,625 to T. A. Edison, 2,493,356 to Mercier et al., 3,220,165 to Howie, and 3,594,991 to Berz show methods and arrangements of apparatus for applying the concept.
Methods and apparatus heretofore described for putting the concept to practical use have been characterized by low operating factors generally attributable to complexity of design or inability to solve the plugging or pressure drop problems caused by accumulations of the entrained solids contained in the feed gas in the apparatus.